-5a - 8a + 2b - b

pleaseee helppp

Aline on the wall and a line on the floor are skew. always, sometimes, or never?

Determine the number of girls in a math class with 87 boys if there are 25 girls for every 75 boys

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters